1. Field of the Invention
This invention relates to a stimulable phosphor sheet cleaning apparatus for removing dust from the surface of a stimulable phosphor sheet used in a radiation image recording and reproducing system wherein the stimulable phosphor sheet is exposed to a radiation to have a radiation image stored therein and is then exposed to stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy, the emitted light is detected and converted into an electric image signal, and a visible image is reproduced by use of the electric image signal.
2. Description of the Prior Art
When certain kinds of phosphors are exposed to a radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, they store a part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to stimulating rays such as visible light, light is emitted from the phosphor in proportion to the stored energy of the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor.
As disclosed in U.S. Pat. Nos. 4,258,264, 4,276,473, 4,315,318 and 4,387,428, and Japanese Unexamined Pat. Publication No. 56(1981)-11395, it has been proposed to use a stimulable phosphor in a radiation image recording and reproducing system. Specifically, a sheet comprising the stimulable phosphor is first exposed to a radiation passing through an object to have a radiation image stored therein, and is then scanned with stimulating rays which cause it to emit light in proportion to the stored radiation energy. The light emitted from the stimulable phosphor sheet when the sheet is exposed to the stimulating rays is photoelectrically detected and converted to an electric image signal, which is processed as desired to reproduce a visible image having an improved quality, particularly a high diagnostic efficiency and accuracy. The finally obtained visible image may be reproduced in the form of a hard copy or may be displayed on a cathode ray tube (CRT). After the light emitted by the stimulable phosphor sheet is detected, radiation energy remaining in the sheet may be released for reuse of the sheet by the method as described, for example, in Japanese Unexamined Pat. Publication No. 56(1981)-12599 and U.S. Pat. No. 4,400,619.
However, when the stimulable phosphor sheet is reused as described above, fine dust floating in the ambient air or arising in the radiation image recording apparatus or the read-out apparatus may stick to the surface of the stimulable phosphor sheet. When dust sticks to the surface on the stimulable phosphor side of the sheet, light emission from the dust sticking portion of the sheet is interrupted by the dust during radiation image read-out, and the portion appears as a blank in a reproduced image. For example, in the radiation image of a cancer source, an object portion calcified by the cancer often appears as a blank in the radiation image. Also, for other diseases, object portions affected by the disease appear as blanks in the radiation images. Therefore, when the image blank is caused by dust, the blank portion is mistaken as a portion affected by a disease.